Industry styling changes have followed consumer demand for more interesting designs and styles. Multicolored rugs currently available are limited to three colors produced by piece-dyeing using yarns of different dye receptivity types to achieve the coloration desired. Commercial and styling demands beyond three colors makes it desirable to provide a multitude of colorations in a given rug product.
Our process of preparing multicolored rugs begins with the use of an initial dyed yarn that is dyed in a multitude of colors, then using the thus dyed yarn and tufting it with undyed yarn of different dye affinity followed by overdyeing to achieve additional colorations. Initial dyeing is accomplished using the space dyeing or intermittent dyeing technique in which the yarn within a given area or space is dyed a particular color, the color and spaces varying throughout the length of the yarn according to random or predetermined orders.
Dyeing carpet yarn is described in U.S. Pat. No. 4,206,735 which relates to a carpet prepared by space dyeing a polyester or polypropylene yarn then tufting the space dyed yarn with another yarn, undyed and having a susceptibility to a dye to which the polyester or polypropylene space dyeing yarn is not susceptible, followed by dyeing the undyed yarn taking care that the selective dyeability of the undyed yarn does not interfere with the previously space dyed yarn. Tak dyeing is used to provide coloration for the nylon tufts and Tak dyeing is explained in U.S. Pat. No. 4,146,362.
Another type of space dyeing is described in U.S. Pat. No. 4,033,717 to Whitaker in which a continuous filament yarn is knit into a prefabric such as a tube or a sock, selectively dyed in a predetermined pattern using various colors, then deknitted, wound onto cones and heated to develop the color. This is also known as a knit/de-knit process. When tufted into a carpet, the tufts of the space dyed yarn are arranged randomly or preferably in predetermined blocks or areas.
Research Disclosure 17913 (Mar. 1979) uses the space dyed yarns of the Whitaker patent, combines them with undyed yarns, then overdyes to a different color to provide a carpet having different color combinations. Space dyed yarns may also be prepared using "resist" techniques to treat the fabric to "resist" the type of dye employed, as described in Jilla, U.S. Pat. No. 3,989,453.
Piece dyeing carpets using carpet pile made from two or more different classes of yarns, one yarn being susceptible to one type of dyeing and the other class of yarns susceptible to a different type of dye, is described in U.S. Pat. No. 3,439,999.
Previously described techniques such as those referred to above were insufficient in retaining the space-dyed coloration of the yarn in the piece-dyed process without the space-dyed coloration bleeding off into the dyebath used for piece dyeing. Also, it was difficult if not impossible to prevent the space dyed yarn itself from being dyed by either the cationic, acid or disperse dyestuffs in the piece dyeing dyebath.